Hot tubs

[Jim W in Tampa]

Friend is wiring his own hot tub . Called me because they want to add 2 ground rods. Tub is 14 feet above ground on wood deck. Does he need ground rods ? I think not. They have #6 ground back to panel. My thinking says if your adding ground rods to system then they need be in number 6 as well because if they ever get open neutral the rods will try to carrry load. Am i right ?

 

[Pierre C Belarge]

Ah, the hottub located above grade...

I believe that since these ground rods are not covered or required, that the rods themselves are supplementary/auxiliary [250.54]. But...the equipotential bonding conductor would still be required to be solid 8AWG or larger [680.26(C)].

 

[Jim W in Tampa]

Ah, the hottub located above grade...

I believe that since these ground rods are not covered or required, that the rods themselves are supplementary/auxiliary [250.54]. But...the equipotential bonding conductor would still be required to be solid 8AWG or larger [680.26(C)].

My concern is they now are part of his service. Just what do you suggest he does about equipotential ? Self contained tub on wood, just what should he do ? I have feeling i will be going there to fix. Hate this kind of job as i know i can't charge him anything because he takes care of my night clubs AC work.

 

[Pierre C Belarge]

Jim
Is your concern that he is required to install a bonding jumper between the hottub rods and the service rods?

That is an interesting thought, if that is what you are thinking. I am going to have to 'noodle' that for awhile.

 

[acrwc10]

My concern is they now are part of his service. Just what do you suggest he does about equipotential ? Self contained tub on wood, just what should he do ? I have feeling i will be going there to fix. Hate this kind of job as i know i can't charge him anything because he takes care of my night clubs AC work.

How far from the service is the hot tub,and what do they think they are gaining by adding two more rods ? If he is a friend explain to him that there is no added safety or protection by adding 2 more ground rods, if he still wants them add them and just let him think he is better off now, they won't help or hurt anything.

 

[hurk27]

How far from the service is the hot tub,and what do they think they are gaining by adding two more rods ? If he is a friend explain to him that there is no added safety or protection by adding 2 more ground rods, if he still wants them add them and just let him think he is better off now, they won't help or hurt anything.

I so agree, Ground rods do little to nothing below 600 volts, and serve no purpose in making this hot tub any safer. I always call them a false sense of security.

My thinking says if your adding ground rods to system then they need be in number 6 as well because if they ever get open neutral the rods will try to carry load. Am i right ?

Never, the impedance of the ground rods will most likely be too high to ever carry the neutral load, and for that fact, that they should never be connected to the load neutral in the first place! this will also just trip the GFCI breaker that is required for the hot tub.

 

[Dennis Alwon]

Does he need ground rods ?

No ground rods are required and in fact may be worthless.

They have #6 ground back to panel

Again this is not necessary unless it is the EGC

My thinking says if your adding ground rods to system then they need be in number 6 as well because if they ever get open neutral the rods will try to carrry load. Am i right ?

The rods will not carry the load at all.

What you may need, and I believe this is open to interpretation, is equipotential bonding under the tub in the ground. Ridiculous yes but I would check with the inspector. We are told it is necessary under a wooden deck.

 

[infinity]

What you may need, and I believe this is open to interpretation, is equipotential bonding under the tub in the ground. Ridiculous yes but I would check with the inspector. We are told it is necessary under a wooden deck.

Even if the deck is 14' above the ground?

 

[Dennis Alwon]

Even if the deck is 14' above the ground?

That is why I said ridiculous but where does the code give us this exception? As far as I know it does not.

 

[mweaver]

Jim,

As Pierre and others have noted, ground rods for this particular installation would be considered auxiliary under the NEC and governed under Section 250.54. Said auxiliary grounding should be connected to the equipment grounding conductor as noted in Section 250.54. Said rods should NOT be connected to the grounded conductor as this would be a violation of Sections 250.6 and 250.54. (at least that is my understanding...)

Section 250.54 directs the reader exactly how to utilize auxiliary grounding, which connections are permitted and especially which connections are not required (specifically Section 250.50).


You do not say this installation is outdoors, but I am assuming that it is.
In either case:
Your review of Part IV of Article 680 (Spas and Hot Tubs), should reveal that both indoor installations (Section 680.43), and outdoor installations (Section 680.42) are subject to Parts I and II of Article 680. Meaning they are both subject to Section 680.26 (Equipotential Bonding).

Your review of Section 680.26(A) should reveal that said equipotential bonding required by this section "shall be installed to reduce voltage gradients in the pool (or in this case the spa-hot tub) area".

While ,admittedly, it is difficult to discern from Section 680.26...

Said equipotential bonding is not required for:
........... - anything separated from the pool (spa-hot tub) by a permanent barrier
........... - anything beyond 5 feet horizontally and 12 feet vertically from the inside wall of the pool (spa-hot tub)
............................... except for metal parts of electrical equipment associated with the pool water circulating system, as noted in Section 680.26(B)(6)
......................................... [said metal parts of (B)(6) require equipotential bonding regardless of location] .


While I can only envision your particular installation, you noted in your post that said installation was "14 feet above ground on wood deck".
Equipotential bonding for an installation is which is isolated on a wooden deck at 14 feet above grade and establishes a reach path greater than 5 feet from the inside wall of the pool appears mute.

While this tends to make many people quite nervous, it is certainly possible that there is actually nothing about your installation which requires any equipotential bonding...


... Yes, there are insurance companies and jurisdictions which will require perimeter bonding to be installed for said elevated wooden deck... Said perimeter bonding for an elevated, isolated wood deck has absolutely no contribution to satisfying the performance requirements outlined in Section 680.26(A) ...

Unfortunately Section 680.26 contains no language to provide any clear direction for installers or enforcement for cases such as the one noted here...


All that being said...
Ultimately this leaves you with providing any equipotential bonding deemed necessary by the AHJ... (which is certainly what I recommend you should do...)

I do hope this is helpful,

mweaver

 

[don_resqcapt19]

Given the rule in 680.26(B)(2) how can you install an outdoor hot tub on a wooden deck and comply with the code? Do you need special conductive wood that can be bonded? Do you put a metal grid over the support joists before you install the deck? Or do you just say the code is all screwed up and forget about bonding the deck?

 

[cschmid]

lets see you add water and 4 people you are now at around 2000 lb's (a ton) I hope the deck is secure. wow...

Back to the bonding issue. if you run a seperate bond and bond all the steel it could come in contact with, what is the issue. whether to install ground rods or not. if he wants rods it is his money.

 

[mweaver]

The Code should NEVER be ignored...

The Code should NEVER be ignored...

Don,

I am unsure if your comments in post #11 were directed at my post, but let me state clearly that I do not believe that "the Code is all screwed up" or that it should be ingored.

It should be applied (as a minimum standard for safety) as noted..., and in this case, equipotential bonding only exists to satisfy the performance requirements in Section 680.26(A).

I am merely stating that perimeter bonding as outlined in Section 680.26(B)(2) exists only to satisfy the performance requirements in Section 680.26(A).

All of 680.26(B) only exists to satisfy the requirements of 680.26(A).


That being said, there are certainly installations and situations where perimeter bonding does not contribute to (A) and would not be necessary. This would be the same as in (B)(1) where the pool shell and all of the associated structural material could be nonconductive. In this same sense (in this example...) there is nothing in (B)(1) to bond, because nonconductive shell bonding will have no contribution to the requirements of Section 680.26(A)...

In no way did I intend that this section should be ignored.
It should be applied in any manner and in all means which will contribute to the performance requirements in 680.26(A).
What one needs to ask themselves (as they are working their way down through 680.26(B) is: What is necessary (for my installation) to meet the performance requirements of 680.26(A)?
(There are certainly installations where parts of 680.26(B) are not applicable to a given installation...)


I believe it is clear that situations can exist where perimeter bonding [just as other sub-sections in 680.26(B)] will have no contribution to the performance requirements of 680.26(A)...

While the language in the 08 NEC is definitely the best we have had to date, the language is not as clear as it could be as to when particular aspects of equipotential bonding are not applicable (to a given installation) because there is no contribution to 680.26(A)...


...Hence the reason (I believe) there is so much misunderstanding surrounding Section 680.26 and its application to installations such as the one noted in post #1...



mweaver

 

[don_resqcapt19]

mweaver,
I am saying that the code is screwed up because it requires the bonding of the wooden deck and that is not possible. There is nothing in 680.26(B)(2) that addresses a non-conductive perimeter surface. And while there is a performace statement in 680.26(A) that does have any effect on the prescriptive requirements of 680.26(B). It is remotely possible that the wooden deck could be come energized and be a hazard, so it really needs to be bonded, but it really can't be, so the code needs to require that all perimeter surfaces have a minimum conductivity so that they can be bonded.

 

[Jim W in Tampa]

I have not seen any part of this set up. Just going by what been told. Did tell him the rods were not needed but if added then need be to code. I told him number 8 solid but rather see it in number 6 ,cost about same. They are going to the grounding block on the tub. If for any reason this house lost a neutral (does happen) then these rods to act as part of the grounding system. He is from the old school of thinking rods do anything . Will admit with amount of lightning we get that they might help the equipment.
As to the idea of supporting a ton of weight that should not be a problem designed right.
All i am saying is that in a default the rods should carry 200 amp fault same as the main ground rods, so i suggested #6 solid. Really se no problem as for equip potential in this case.

 

[hurk27]

All i am saying is that in a default the rods should carry 200 amp fault same as the main ground rods, so i suggested #6 solid. Really se no problem as for equip potential in this case.

Jim this is wrong thinking!

Ground rods do not have enough impedance to earth to ever carry fault current, NEVER!

Ohms law will show us that even if you get a 25 ohm resistance to earth, at 120 volts would only give you 4.8 amps of fault current to the ground rod! thats it. that would not even open a 5 amp fuse much less a 15 or 20 and certainly not a 40 or 50 amp breaker.

Even the service ground rod wont do this, or is it intended to do this. The only intention in the code for a ground rod is to help limit the voltage in a case where the high primary voltage were to come into contact with the secondary conductors, and at best the rod would be very limited in this case. the other reason the code mentions is for lightning protection, but let me tell ya, one or two rods don't work there either. thats why I don't like the false sense of security people think they have using rods as an electrode, systems above 600 volts they work fine but below they do little to nothing.

 

[ibew501ed]

Jim this is wrong thinking!

Ground rods do not have enough impedance to earth to ever carry fault current, NEVER!

Ohms law will show us that even if you get a 25 ohm resistance to earth, at 120 volts would only give you 4.8 amps of fault current to the ground rod! thats it. that would not even open a 5 amp fuse much less a 15 or 20 and certainly not a 40 or 50 amp breaker.

Even the service ground rod wont do this, or is it intended to do this. The only intention in the code for a ground rod is to help limit the voltage in a case where the high primary voltage were to come into contact with the secondary conductors, and at best the rod would be very limited in this case. the other reason the code mentions is for lightning protection, but let me tell ya, one or two rods don't work there either. thats why I don't like the false sense of security people think they have using rods as an electrode, systems above 600 volts they work fine but below they do little to nothing.

excellent post and a lot of electricians dont think that way

 

[mweaver]

Wayne has an excellent point in post #16

Wayne has an excellent point in post #16

Wayne,

Excellent Post!

You have hit this point right on the head...

Who Knew! All this grounding and bonding actually just boils down to ohm's law!

(This is how it is taught in the Soares Book ver 9 & 10 published by the IAEI ...A definate MUST read...)

mweaver

 

[LarryFine]

In this same sense (in this example...) there is nothing in (B)(1) to bond, because nonconductive shell bonding will have no contribution to the requirements of Section 680.26(A)...

Oh, sure, and the next thing we know, you'll be telling us we don't have to bond plastic water piping. :wink:

 

[LarryFine]

excellent post and a lot of electricians dont think that way

What's scarier is how may POCO field guys think ground rods should compensate for open neutrals, or that measuring 120v/120v with no load on the service means something useful. I've faced that personally more than twice in the past couple of years. :roll: